Known in the art is a dc-to-ac converter built around a multivibrator associated with the output of a dc voltage source via a voltage regulator built around a composite transistor. The voltage regulator is provided with a parametric voltage stabilizer comprising a ballast resistor and a Zener diode. The emitters of the multivibrator transistors are interconnected, while the collectors are connected to the terminals of the primary winding of an output transformer also having a feedback winding. Also connected to the primary terminals of the transformer is a rectifier comprising a plurality of diodes arranged in a series opposition.
The converter includes an additional diode connected in a forward direction between the point of connection of the anodes of the rectifier diodes and the collector of the composite transistor (cf. USSR Inventor's Certificate No. 440,752; Cl. HO2m 3/24).
The prior art converter provides for normal operation when the supply voltage exceeds the rated value only 1.5 to 1.8 times. A further increase in the supply voltage, e.g. two- or three-fold (in particular, when the dc voltage increases from 9 to 30 V), adversely affects the operation of the parametric stabilizer and multivibrator transistors because the additional diode is rendered conducting, and the supply voltage is directly impressed upon the anodes of the diodes connected in series opposition and upon the ballast resistor of the parametric stabilizer.
As a result, the diodes of the rectifier are made nonconducting by the supply voltage which exceeds the voltage rectified by the diodes, while the Zener diode becomes connected to the dc voltage source via the ballast resistor.
This reduces the stability of the output ac voltage, and the power dissipated across the composite transistor of the voltage regulator substantially increases.